This invention relates to a method and apparatus for determining when a memory allocation for a page in a printer or a copier should be discontinued and, more particularly, to such a method and apparatus that only deallocates memory for a page when that page has been output from a page handling accessory to the ultimate user.
Currently, printers and copiers, after a page has been printed and sent to an output bin, deallocate memory set aside for the page. Such memory allocation/deallocation is accomplished by a page management process. Once the page is sent to the output bin, it is considered as having been successfully printed by the page management process. So long as the output bin comprises a portion of the native printer/copier, it is assured that a page ejection signal issuing from the output bin indicates successful output of the page.
However, some customers attach third party media sheet handling apparatus to printer/copiers to perform additional functions with respect to the print job that includes the page. For instance, such functions may include stapling, embossing, binding, etc. If a jam or other error occurs at the page-handling accessory, no methodology exits to inform the page management process of the jam or error and, further, to enable a reprint of the print job from a given page number.
For example, if a printer/copier is working on page 6 of seven-page job, the page-handling accessory may include a complicated path that causes it to be working on page 2 when it incurs an error or a jam. Under such circumstances, it is desirable that the page handling accessory device have the ability to inform the printer/copier to flush its page buffer and to restart printing from page 2.
The prior art includes a number of teachings with respect to responding to a paper jam or other printer/copier page movement problem. For instance, U.S. Pat. No. 5,680,522 to Kasai describes a printer system that responds to a paper jam by causing the bit map data of the jammed page, that is kept in the page buffer, to be sent again to a receiving buffer so that it can be reproduced. U.S. Pat. No. 5,413,419 to Oami et al. describes a paper jam recovery procedure wherein page data is accessed from either a first buffer memory or a second memory which includes raster image data, depending upon the particular page that has caused the jam. A similar jam recovery system is disclosed in U.S. Pat. No. 5,210,823 to Moroi. More specifically, a printing control apparatus recovers a jammed page by using the page intermediate descriptors stored in a page descriptor area of memory. In the case where the print data has been saved to a separate area, that print data is used. Further, in a case where the print data includes a substantial amount of image information, raster image information that has been saved in a bit map memory is utilized.
While the above-indicated prior art describe a variety of methods for recovering print data for a jammed page, it does not take into account the problem that arises when the printer/copier believes that it has successfully ejected a page to the output bin but apparatus which post processes the page creates the jam action.
Accordingly, there is a need for a page recovery action that can respond to recover a page in the event that a jam occurs in a page handling accessory that is not part of the native printing/copying device.
The invention assures that page data in a printer/copier memory is retained until the corresponding page is successfully output to an attached page handling accessory. The system incorporating the invention includes a memory with storage regions allocated to store page data to be printed, a print engine that is responsive to the page data to output printed pages, and an output tray for receiving printed pages from the print engine and for providing a first signal indicative of such receipt. A paper handling accessory is coupled to the output tray for further processing of the printed pages and is constructed to provide a second signal that is indicative of a page output therefrom after its handling actions are completed. A processor is controlled by a page management process to deallocate storage areas allocated to a page upon receipt of both the first signal and the second signal, indicating that the page has successfully exited from the page handling accessory.